1. Field of the Invention
The present invention relates to an acoustic structure which prevents acoustic problems or troubles in an acoustic space and which adjusts sounds in the acoustic space to sounds that are pleasant to listen to.
2. Description of Related Art
In an acoustic space, such as an interior of a room, enclosed with walls, there may be caused acoustic troubles, such as booming and flutter echoes, by sounds that are repeatedly reflected between the walls opposed parallel to each other. The following Patent Literature 1 discloses a technique of preventing such acoustic troubles. FIG. 18 is a view for explaining an acoustic structure disclosed in the Patent Literature 1. The acoustic structure shown in FIG. 18 includes cavities 22-i (i=1 to 6) defined by plates 18, 19, 20, 21, 11-i (i=1 to 7), and openings 21-i (i=1 to 6) are formed in the front-side plate 18. The acoustic structure is installed on an inner wall or a ceiling of an acoustic space such that the openings 21-i (i=1 to 6) are oriented toward an inside of the acoustic space. When sounds enter the acoustic structure from the acoustic space, each of the cavities 22-i (i=1 to 6) of the acoustic structure resonates with a sound of a corresponding specific resonance frequency among sounds that enter the openings 21-i (i=1 to 6) from the acoustic space. The resonated sounds are emitted from the cavities 22-i (i=1 to 6) to the acoustic space through the respective openings 21-i (i=1 to 6), whereby sound scattering and sound absorbing effects are produced near the openings 21-i (i=1 to 6). As a result, it is possible to prevent the acoustic troubles such as booming and flutter echoes.
As shown in FIG. 18, in the acoustic structure disclosed in the Patent Literature 1, sound absorbing members 30-i (i=1 to 7) are attached to the front-side plate 18, whereby the sound scattering and sound absorbing effects produced near the openings are increased. In addition to the arrangement in which the sound absorbing members are attached to the front-side plate 18, the Patent Literature 1 further discloses an arrangement in which the cavities 22-i (i=1 to 6) are filled with the sound absorbing members.
Patent Literature 1: JP-A-2012-3226